Print hammer for a printing machine

ABSTRACT

A print hammer for a printing machine, particularly for a highspeed printing machine having a rotating or translating type support, comprising an impact beam, two supporting members for supporting the impact beam and at least one clamping means, the impact beam being movable in a direction parallel to its center line and relative to the clamping means, the supporting members during the displacement of the impact beam being subjected to bending. The impact beam, the supporting members and the clamping means are manufactured from the same material, preferably a synthetic resin, and constitute a hammer body which consists of a single part. The print hammer is particularly suitable for an electro-dynamic drive and comprises for that purpose an embedded magnet coil and embedded current conductors.

United States Patent 1 1 Lenders et a1. May 29, 1973 [541 PRINT HAMMER FOR A PRINTING 3,279,362 10/1966 Helms ..101 109 x MACHINE 3,282,203 11/1966 Kalbach 1211.. .....101/93 (3 3,285,166 11/1966 Helms et al. ..101/93 C Inventor-S1 Wllhelmus Leonard L0uI f 3,334,409 8/1967 Shneider et a1... ..29/428 Hendrik Alle Post; T wan Khlng Sie, 3,354,820 11/1967 Braxton ..101/93 C all Of Emmasingel, Eindhoven; 3,359,921 12/1967 Arnold et al.. .....lO1/93 C Johannes Mattheus visscher; Marius 3,447,455 6/1969 Shneider 101/93 C Quirijnen, both of Rijswijk, Netherlands Primary Examiner-William B. Penn Attorney-Frank R. Trifari [73] Assigneez U.S. Philips Corporation, New

York, 57 ABSTRACT 1 Filedi g- 1970 A print hammer for a printing machine, particularly [2]] APPL NOJ 63,469 for a high-speed printing machine having a rotating or translating type support, comprising an impact beam, two supporting members for supporting the impact 1 1 Foreign Application Data beam and at least one clamping means, the impact 29 h a 693289 beam being movable in a direction parallel to its center line and relative to the clamping means, the [52] U S Cl l0l/93C supporting members during the displacement of the [51] In. .0 ...B4lj 9/00 impact beam being Subjected to bending. The impact ['58] Fieid C 09 beam, the supporting members and the clamping means are manufactured from the same material, preferably a synthetic resin, and constitute a hammer body which consists of a single part. The print [56] kef'erencesclted hammer is particularly suitable for an electro-dynamic UNITED STATES PATENTS drive and comprises for that purpose an embedded 1 magnet coil and embedded current conductors. 3,172,352 3/1965 Helms ..lO1/93C 3,172,353 3/1965 Helms 101/93 C 7 Claims, 6 Drawing Figures 31 i K l l as 37 l l I -1 PATENTEU NAYZ 91973 SHEET 1 or 2 Fig.1

INVENTORS WILHELMUS L-LJ-ENDERS HENDRIK A- POST TJVIQN KI'HNG SIE JOHANNES M VISSCNER BY MARIUS OUIRIJEN AGENT PRINT HAMMER FOR A PRINTING MACHINE The invention relates to a print hammer for a printing machine comprising an impact beam and two elongate flexible supporting members which are connected at one end to the impact beam and at the other end comprise means for clamping the print hammer on a stationary supporting block, the supporting members, in the rest position of the print hammer, extending substantially in parallel, the impact beam being movable relative to the clamping means in a direction parallel to its center line, the supporting members, during the displacement of the impact beam, being subjected to a bending over at least part of their length.

Such print hammers are used in printing machines, inter alia in high speed printing machines which comprise a rotating or translating type support. The print hammers can be driven mechanically, electromagnetically or electrodynamically. It is required that the movement and impact times of the impact beam be as short as possible and remain constant so as to obtain a high impact frequency and a true uniform reproduction of the characters to be printed. Contradictory requirements are imposed upon the impact beam and the supporting members; the impact beam should be resistant to wear and rigid, whereas the supporting members must fulfil a resilient function, while furthermore the mass of the print hammer must be as small as possible.

A print hammer is already known which is composed of a large number of elements, usually of small dimensions, and in which in particular the impact beam, the supporting members and the clamping means are manufactured from different materials. The assembly of said elements to form a print hammer is very timeconsuming and expensive and requires a great accuracy of the prefabricated elements. This known print hammer is of such a construction that the connection of the supporting members to the impact beam presents problems; in course of time the supporting members can break at the area of the connection.

It is the object of the invention to provide a compact print hammer which avoids these drawbacks and which can be manufactured in a rapid and cheap manner with great accuracy and reproducibility.

In order to achieve this end, the impact beam, the supporting members and the clamping means are manufactured mainly from the same material and constitute a hammer body which consists of a single part which has been obtained in a mould. Since the hammer body consists of one single part, connection problems, in particular of the supporting members to the impact beam, are prevented. Since the hammer body has been manufactured in a mould by moulding or' injection moulding, an optimum functional shape can easily be given to the impact beam and to the supporting members; inspite of the fact that thesecomponents are mainly manufactured from the same material, the above contradictory requirements are met at least fo a considerable part.

According to a preferred embodiment of the print hammer according to the invention, the hammer body is manufactured from a flexibly deformable synthetic resin. The properties inherent in a synthetic resin, for example, small mass, flexibility, damping, possibility of moulding, injection moulding, and so on, meet the multiple requirements emposed upon a print hammer in an excellent manner. Synthetic resin is extremely suitable, for injection moulding. The hammer body manufactured from synthetic resin has a small mass so that the inertia and hence the movement and contact times are minimized. Pressure waves to which the print hammer is subject are attenuated by the damping properties of the synthetic resin. Subsequent machining of the moulded or injection moulded hammer body is not necessary.

According to another preferred embodiment of the print hammer according to the invention, the part of the supporting members which is subject to bending shows a cross-section which increases from a minimum cross-section in the center of said part towards the two ends thereof. By giving the parts of the supporting members which are subject to bending a shape having a non-constant cross-section an even stress distribution over the length of said parts and during bending hereof is obtained so that the lifetime of the print hammer, in particular of the supporting members, is substantially unlimited. The cross-section may be variable both in one and in two directions.

A further preferred embodiment of the print hammer according to the invention is characterized by a rectangular cross-section the width of which is constant throughout its length and is at least equal to the thickness of the impact beam. As a result of this a high rigidity transverse to the direction of movement of the impact beam is obtained. The cross-section of the supporting members is variable only in a direction parallel to the center line of the impact beam.

In order to prevent a notch effect at the transitions of the supporting members on the impact beam and the clamping means, according to an advantageous embodiment of the print hammer according to the invention the supporting members at their ends adjoin the impact beam and the clamping means in a smooth manner.

According to another preferred embodiment of the print hammer according to the invention the hammer body has the shape of a frame which is closed on all sides, the clamping means forming one assembly with a common connection beam. Such a construction of the hammer body can be mounted easily and accurately on a supporting beam. The possibilities of damage to the hammer body and of undesired deformation of the supporting members during transport and assembly are substantially excluded.

In a preferred embodiment of the print hammer according to the invention the hammer body is manufactured of polyacetal. Experiments have demonstrated that a print hammer having a hammer body made of polyacetal has a much longer lifetime than, for example, the known print hammer, the impact beam of which is manufactured from aluminum. On the basis of the large resistance to wear of polyacetal the impact face of the impact beam is deformed only slightly also after prolonged useso that an accurateand even reproduction 'of the characters to be printed is ensured during a large number of strokes. As a result of the low detrition of the impact face, the distance to be covered by said face and hence the travel time remain substantially constant.

In order to be able to adapt the rigidity of the impact beam and the flexible properties of the supporting members to different requirements, the hammer body according to a further embodiment of the print hammer according to the invention comprises at least partly an embedded reinforcement. Glass fibers are preferably used as a reinforcement for the supporting members, and glass fibers metal or another suitable material the rigidity of which is larger than that of the synthetic resin, are preferably used as a reinforcement for the impact beam. The advantage of glass fibers is that they can easily be combined with a synthetic resin in which a good adhesion between the synthetic resin and the glass fibers is obtained.

The above-described print hammer is particularly suitable for electrodynamic drive, the impact beam comprising a flat magnet coil supported by a coil support and the axis of which is at right angles to the direction of movement of the impact beam, the print hammer comprising means for supplying current to the magnet coil. According to the invention this print hammer is characterized in that the magnet coil is embedded in the hammer body, the coil support forming one assembly with the impact beam. In the known print hammer the coil with the coil support is secured to the impact beam during assembly. This activity is made superfiuous by moulding or injection moulding of the magnet coil, as a result of which in addition an accurate arrangement of the coil relative to the impact beam is obtained.

The provision of the current conductors is simplified in that according to a further characteristic feature of the print hammer according to the invention the impact beam, the supporting members and the clamping means comprise embedded current conductors.

In order that the invention may be readily carried into effect, a few examples thereof will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which FIG. 1 is a longitudinal cross-sectional view of an example of a print hammer according to the invention taken on the line I-I of FIG. 2,

FIG. 2 is a side elevation of the print hammer shown in FIG. 1,

FIG. 3 is a plan view of the print hammer FIGS. 4, 5 and 6 show further embodiments of the print hammer according to the invention.

The print hammer 1 shown in FIGS. 1, 2 and 3 comprises an impact beam 3 which is supported by two elongate supporting members 5 which in the rest position extend parallel to each other and transverse relative to the center line of the impact beam 3. The supporting members 5 each adjoin with one end 7 the impact beam 3 and with the other end 9 a thickened clamping means 11. The impact beam 3, the supporting member 5 and the clamping means 11 are manufactured from the same material, preferably from a flexibly deformable synthetic resin and constitute a hammer body 13 consisting of one single part which has been obtained by moulding or injection moulding in a mould. Polyacetal is preferably used as the synthetic resin. The impact beam 3 can be moved relative to the clamping means 11 in a direction parallel to its center line. During the movement of the impact beam 3, the supporting members 5 are flexibly deformed. The cross-section of the supporting members 5 is rectangular and, viewed in a direction parallel to the direction of movement of the impact beam 3, increases from a minimum cross-section in the central part towards the two ends 7 and 9, while the thickness of the supporting members 5, viewed in a direction transverse to the direction of movement of the impact beam, is constant throughout its length and equal to the thickness of the impact beam. By means of two curved portions 15 situated on either side of their center line, the supporting members 5 adjoin the impact beam 3 and the clamping means 11. As a result of the above-described design of the supporting members 5, a substantially uniform distribution of the stresses caused by the bending is obtained throughout their length.

The print hammer 1 shown is driven electrodynamically and comprises for that purpose a coil support 17 which forms one assembly with the impact beam 3 and I is manufactured from the same material, and a fiat embedded magnet coil 19 the axis of which extends at right angles to the direction of movement of the impact beam 3. The magnet coil 19 may consist of a number of wire or ribbon windings. In addition to the magnet coil 19, the current conductors 21 which preferably consist of the ends of the coil windings, and the connection pins 23 for supplying current to the magnet coil, are embedded during the moulding or injection moulding of the hammer body. The apertures 25 in the impact beam 3 and 27 in the coil support 17, are caused by pins in the mould for localizing the current conductors 21 and the magnet coil 19 during the moulding or injection moulding. In the embodiment shown the magnet coil 19 is arranged asymmetrically relative to the hammer body 13. If desirable the magnet coil can be provided as such in the center of the impact beam 3.

FIG. 1 furthermore diagrammatically shows the essential elements of a high speed printing machine known per se. The impact face 29 of the impact beam 3 of the print hammer 1 is arranged opposite to a rotating drum 31 on the circumference of which the characters 33 to be printed are present in relief and in juxtaposed circumferential tracks one of which is shown in FIG. 1. Each track comprises all the characters which it is desirable to print while the number of tracks is equal to the total number of characters which can be printed on one and the same line. Between the drum 31 and the impact face 29, an inked ribbon 35 and a paper strip 37 are present. The clamping means 11 are each rigidly clamped to a fixed supporting block 39 while the connection pins 23 are connected to a current supply 41. Since the hammer body 13 is manufactured from a synthetic resin, insulation problems do not occur. On either side of the hammer body 13 at the area of the magnet coil 19 stationary permanent magnets 43 are arranged, the oppositely located poles of which are opposite. Opposite to each circumferential track of the drum 31 a print hammer is arranged. The drum 31 rotates at a speed in the order of 1,000 r.p.m., each print hammer being energized during each revolution of the drum at the correct instant for printing the desired characters by means of a control circuit. By supplying current to the magnet coil 19 the magnet coil, and hence the impact beam 3, are moved in the direction of the drum 31 by the Lorenz force. The impact face 29 of the impact beam 3 impacts against the paper strip 37, as a result of which said strip together with the inked ribbon 35 is pressed against the drum 31 so that the selected character 33 is printed on the paper strip 37. The impact energy is sufficient to return the print hammer to its original position. During each revolution of the drum 31 a full line can be printed and after each revolution the paper strip 37 is moved stepwise.

FIG. 4 shows another embodiment of the print hammer according to the invention, in which the hammer body 13 has the shape of a frame 45 which is closed on all sides and in which the clamping means 11 directly adjoin a common connection beam 47. This construction enables the mounting of the print hammer on a supporting block in a simple manner. Because of the rigid construction of the hammer body the hammer is is particularly suitable for mechanical drive, for electrodynamic drive. It can however, be provided with a moulded magnet coil and moulded current conductors. The magnet coil need not necessarily be embedded but may also be provided in a gap on the impact beam 3 which is denoted by 49 in FIG. 4. In order to increase the rigidity of the impact beam 3 and to prevent bending thereof with certainty, a reinforcement 51 which may consist of metal, glass fibers of another material the rigidity of which is larger than that of the synthetic resin, can be embedded in the impact beam during the moulding or injection moulding. The supporting members 5 may also comprise an embedded reinforcement 53, preferably of glass fibers, as a result of which the flexible properties can be adapted to different requirements in a desirable manner. Similarly the connection beam 47 may be provided with a reinforcement 55 so as to prevent a deformation of the beam during clamping. FIG. 4 shows the transition of the clamping means 1 l on the connection beam 47, but a significant separation between said components need not be visible.

FIGS. 5 and 6 show further possible embodiments of the print hammer according to the invention. The hammer body of the print hammer shown in FIG. 5 also has the shape of a closed frame. During the displacement of the impact beam 3 the supporting members 5 are subjected only over a part of their length to a bending and comprise near their two ends 7 and 9 two bending portions 57 which have a variable cross-section and are connected by a central portion 59 of a constant crosssection. I

FIG. 6 is a side-elevation of a print hammer in which the supporting members 5 have a cross-section the width b of which is substantially constant throughout the length of the supporting members and is larger than the thickness d of the impact beam 3. As a result of this design of the supporting members a hammer body is obtained which has a particularly large rigidity in the transverse direction.

By changing the dimensions of the parts of the supporting members which are subject to bending the flexible properties thereof can be influenced.

The print hammer according to the invention can advantageously be used in any type of printing machine but the advantages hereof are obtained particularly when it is used in a high-speed printing machine.

What is claimed is:

l. A print hammer for a printing machine comprising an impact beam, said impact beam having an impact face formed at one end thereof adapted to cause pressure impact against a print member, a pair of flexible supporting members attached at one end thereof to and extending from said impact beam substantially parallel to each other when said print hammer is in the stationary position, a thickened portion formed at the other end of said flexible supporting members forming means for clamping said print hammer to a stationary support block at the ends of the supporting members remote from the impact beam, said impact beam, said impact face said supporting members and said clamping means being integrally made of the same flexibly deformable synthetic resin, so as to form a unitary construction.

2. The print hammer according to claim 1 wherein the cross-section of said supporting members is rectangular having a width running in a direction transverse to the directional movement of the impact beam is constant throughout the length of said supporting member and is at least equal to the thickness of the impact beam.

3. The print hammer according to claim 2 wherein the portion of said supporting member being subjected to bending has a width when viewed in a cross-section taken parallel to the direction of movement of said impact beam which increases from a minimum at the center of said supporting member toward the ends thereof.

4. The print hammer according to claim 1 further comprising a connection beam formed integrally with said clamping means so that said print hammer is formed having a framed construction.

5. The print hammer according to claim 1 wherein said synthetic resin is a polyacetal.

6. The print hammer according to claim 1 further comprising reinforcement means embedded within said supporting members and said impact beam.

7. The print hammer according to claim 4 further comprising reinforcement means at least partially embedded within said impact beam, said supporting members and said connection beam. 

1. A print hammer for a printing machine comprising an impact beam, said impact beam having an impact face formed at one end thereof adapted to cause pressure impact against a print member, a pair of flexible supporting members attached at one end thereof to and extending from said impact beam substantially parallel to each other when said print hammer is in the stationary position, a thickened portion formed at the other end of said flexible supporting members forming means for clamping said print hammer to a stationary support block at the ends of the supporting members remote from the impact beam, said impact beam, said impact face said supporting members and said clamping means being integrally made of the same flexibly deformable synthetic resin, so as to form a unitary construction.
 2. The print hammer according to claim 1 wherein the cross-section of said supporting members is rectangular having a width running in a direction transverse to the directional movement of the impact beam is constant throughout the length of said supporting member and is at least equal to the thickness of the impact beam.
 3. The print hammer according to claim 2 wherein the portion of said supporting member being subjected to bending has a width when viewed in a cross-section taken parallel to the direction of movement of said impact beam which increases from a minimum at the center of said supporting member toward the ends thereof.
 4. The print hammer according to claim 1 further comprising a connection beam formed integrally with said clamping means so that said print hammer is formed having a framed construction.
 5. The print hammer according to claim 1 wherein said synthetic resin is a polyacetal.
 6. The print hammer according to claim 1 further comprising reinforcement means embedded within said supporting members and said impact beam.
 7. The print hammer according to claim 4 further comprising reinforcement means at least partially embedded within said impact beam, said supporting members and said connection beam. 